The objective of this project is to study the structure and role of carbohydrate in plasma membranes of normal and neoplastic cells. Our initial aim was to develop analytical micro-methods that would permit the study of carbohydrate moieties in picomolar amounts of glycoproteins. The newly developed techniques were employed in elucidation the structure of Thy 1.1 and Thy 1.2 antigens from mouse lymphoblastoid cell lines and from brain. Further experiments were projected to isolate and characterize Thy 1 antigens of human brain and of mouse mammary tumor cells. Chemical methods of modification of the carbohydrate moiety of glycoproteins are being studied that will allow examination the role of sugars in the antigenic activity in cell surface components. We also propose to investigate the structure and role of carbohydrates in the molecule of secretory component isolated from the plasma membranes of human colonic cancer cells.